Measuring instrument for intracardial acquisition of the blood oxygen saturation of a patient for controlling the pacing rate of a heart pacemaker
First Claim
1. An instrument for intracardial acquisition of blood oxygen saturation in a sequence including making a reference measurement and a useful signal measurement, said instrument comprising:
- a measuring probe having two leads, a light transmitter, means for generating said useful signal connected between said leads including a measuring current path having said light receiver therein, said light transmitter and light receiver disposed such that said light receiver receives light from said light transmitter reflected by the blood dependent on the degree of oxygen saturation of said blood;
an evaluation circuit connected to said measuring probe leads, said evaluation circuit supplying one applied signal for each sequence, said applied signal having non-changing polarity and being used for enabling both said reference measurement and said useful signal measurement; and
means for separately generating said reference signal and said useful signal in sequence in response to said applied signal.
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Accused Products
Abstract
A measuring instrument for the intracardial acquistion of the blood oxygen saturation of a patient for use in controlling a heart pacemaker implanted in the patient has a measuring probe with a measuring current path which includes a light transmitter and a light receiver which receives light emitted by the light transmitter and reflected by the blood. The measuring probe is connected to an evaluation circuit via two lines. A useful signal measurement and a reference measurement, independent of the blood reflection, are made and the blood oxygen saturation is identified by comparing the two signals. A separate evaluation of the useful signal measurement and the reference signal measurement is enabled by making the useful signal measurement chronologically offset with respect to the reference measurement in one embodiment, or by using the amplitude of the current from the light receiver to make one measurement, and using the voltage amplitude to make the other measurement in another embodiment.
109 Citations
19 Claims
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1. An instrument for intracardial acquisition of blood oxygen saturation in a sequence including making a reference measurement and a useful signal measurement, said instrument comprising:
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a measuring probe having two leads, a light transmitter, means for generating said useful signal connected between said leads including a measuring current path having said light receiver therein, said light transmitter and light receiver disposed such that said light receiver receives light from said light transmitter reflected by the blood dependent on the degree of oxygen saturation of said blood; an evaluation circuit connected to said measuring probe leads, said evaluation circuit supplying one applied signal for each sequence, said applied signal having non-changing polarity and being used for enabling both said reference measurement and said useful signal measurement; and means for separately generating said reference signal and said useful signal in sequence in response to said applied signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An instrument for intracardial acquisition of blood oxygen saturation using a measuring probe having two leads in a sequence including making a reference signal measurement and a useful signal measurement, said instrument comprising:
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a light transmitter connected in said measuring probe between said leads; a measuring current path in said measuring probe connected between said leads including a light-sensitive diode and a resistor connected in series therewith; a normally open switch having a conducting path connected between said leads and a control terminal connected to a junction between said light-sensitive diode and said resistor; a capacitor connected in parallel with said light-sensitive diode between said junction and one of said leads; and an evaluation circuit connected to said leads which supplies a pulse to said measuring probe for each sequence and which measures the voltage across said leads, whereby said pulse initially energizes said light transmitter with said normally open switch being non-conducting for making said reference signal measurement and charging said capacitance by the action of said light from said transmitter on said light sensitive diode reflected by the blood oxygen, said normally open switch closing upon attainment of said selected charge on said capacitance for making said useful signal measurement. - View Dependent Claims (16, 17)
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18. An instrument for intracardial acquisition of blood oxygen saturation using a measuring probe having two leads in a sequence including making a reference signal measurement and a useful signal measurement, said instrument comprising:
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a first switch having a conducting path connected between said leads and a control electrode connected to one of said leads; a light transmitter connected in series with a conducting path of a second switch between said leads, said second switch having a control electrode; a voltage divider connected in parallel with said conducting path of said first switch and having a tap connected to said control electrode of said second switch; a light receiver connected between said leads, said light receiver disposed for receiving light from said light transmitter reflected by said blood oxygen and generating a current proportional thereto; and an evaluation circuit connected to said leads which supplies a continuously rising signal to said measuring probe and which measures the voltage across said leads, whereby said first and second switches are respectively responsive to said continuously rising signal such that said first switch is initially closed and said second switch is initially open during said reference signal measurement, and said first switch is thereafter opened and said second switch is thereafter closed for making said useful signal measurement. - View Dependent Claims (19)
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Specification